Melanoma Risk Factors

The Risks. The Causes. What You Can Do.

Skin cancers like melanoma have damaged DNA (mutations) in skin cells that lead to uncontrolled growth of these cells. Ultraviolet (UV) rays from the sun or tanning beds damage DNA in your skin cells. Your immune system repairs some of this damage but not all. Over time, the remaining DNA damage can lead to mutations that cause skin cancer. Many other factors also play a role in increasing the risk for melanoma, including genetics (family history), skin type or color, hair color, freckling and number of moles on the body.

Understanding what causes melanoma and whether you’re at high risk of developing the disease can help you prevent it or detect it early when it is easiest to treat and cure.

These factors increase your melanoma risk:

  • Many moles: The more moles you have on your body, the higher your risk for melanoma. Also, having large moles (larger than a tip of a pencil eraser), or any atypical moles, increases the risk for melanoma.
  • Fair skin: Melanoma occurs more frequently in people with fair skin, light eyes and light or red hair.
  • Skin cancer history: People who have already had melanoma or nonmelanoma skin cancers run a greater risk of developing melanoma in the future.
  • Genetics: Melanoma can run in families – one in every 10 patients has a family member who also has had the disease.

UV exposure

There is a clear correlation between unprotected exposure to UV radiation and melanoma. UV rays from the sun and indoor tanning are a powerful attack on the skin and the primary risk factor for developing melanoma and other skin cancers. Frequent severe sunburns in early childhood can especially increase melanoma risk, but sunburns later in life and cumulative exposure also play an important role.

Find out more about the risks associated with UV radiation.

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of developing melanoma
with a history of 5 or more sunburns.

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Weakened immune system

If your immune system is weakened as the result of medical treatments, including chemotherapy or immunosuppressive therapy (commonly used after an organ transplant), or if you have a medical condition such as lymphoma or HIV that compromises the immune system, your risk of developing melanoma is higher.

Many moles

Moles, the small brown “beauty marks” that arise on the skin throughout life are not dangerous, but people with many moles are at increased risk for developing melanoma. While most melanomas develop in normal skin and it’s less common for melanoma to develop in an existing mole, it does happen. About 20-30 percent of melanomas arise from existing moles.

Atypical moles (some physicians call them dysplastic nevi) are often larger than a tip of a pencil eraser and can have irregular borders and multiple color hues. They can resemble melanoma but they are not cancerous or precancerous. People with many moles and those with many atypical moles are at very high risk for developing melanoma.

Because melanoma can develop in a mole or can develop in normal skin, it is important to see your dermatologist if you see a new or changing mole.

Fair skin

Although anyone can get melanoma, people with fairer skin – especially those with red or blond hair, blue or green eyes, or skin that freckles or easily burns – have a higher risk. If you don’t know your skin type, take the quiz and find out here.

Skin cancer history

Previous skin cancer diagnoses also increase your risk for developing melanoma. If you’ve had melanoma already, you run a risk for recurrence. You also run a risk for developing new melanomas. If you’ve had squamous cell carcinoma or basal cell carcinoma, you are also more likely to develop melanoma at some point in your life.

Genetic risk factors

Family history

Melanoma can run in families. In fact, about one in every 10 patients diagnosed with melanoma has a family member with a history of the disease. If one or more close biological relatives – parents, brothers, sisters or children – had melanoma, you are at increased risk. Compared to people with no family history of melanoma, each person with a first-degree relative diagnosed with melanoma has a greater chance of developing the disease. That’s why, when a melanoma is diagnosed, doctors often recommend that close relatives be examined for melanoma.

Familial atypical multiple mole melanoma syndrome (FAMMM)

If you have hereditary risk factors as well as many atypical moles, your risk of developing melanoma is even higher. This combination of family history and having many unusual moles is often referred to as Familial Atypical Multiple Mole Melanoma syndrome (FAMMM).

Genetic discoveries

In the case of some familial melanomas, researchers have discovered DNA changes in tumor suppressor genes, including CDKN2A (cyclin-dependent kinase inhibitor 2A) and BAP1 (BRCA1 associated protein-1). These changes prevent the genes from doing their normal job of controlling cell growth, giving damaged cells less chance to repair before progressing to cancer. Another tumor suppressor gene, MC1R (melanocortin 1 receptor) also increases the risk for melanoma. Families suspected of having melanoma genes can be screened to identify members that carry a defective gene.

What you can do

Be on the lookout: If you have FAMMM or other hereditary risk factors, be sure to self-check more frequently and visit your dermatologist often for thorough professional skin exams.

Start early: Children in melanoma-prone families need special attention. Some doctors recommend skin checks at puberty and during adolescence.

The good news is that the survival rate for familial melanoma is even higher than that for non-familial melanomas – most likely because these families are carefully watching and melanomas are usually found while the cancer is very early and more likely to be cured.

Protect against UV rays: You can reduce the melanoma risk posed by UV radiation by taking simple, smart protective measures. Safeguard your skin against the sun every day, even when it’s cloudy. Avoid indoor tanning entirely. Get more details here: Skin Cancer Prevention Guidelines.

Reviewed by:
Allan C. Halpern, MD

Ashfaq A. Marghoob, MD
Ofer Reiter, MD 

Last updated: June 2021 

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Last updated: January 2024

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